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Sprint launches femtocell cellular-to-WiFi service

Sprint is the first major mobile carrier to introduce femtocell service to two …

Wireless provider Sprint has begun offering femtocell service in select markets that will allow customers to use their cell phones in otherwise low-signal areas, such as underground and deep within buildings. The service, called Sprint Airwave, will not only allow customers to extend and boost their cell signal at home, but also lets them make unlimited calls while on the Airwave service without using precious plan minutes. The service costs a flat fee of $15 per month on top of the customer's regular cell phone bill, or $30 per month for households with multiple users.

Femtocells allow users to transition seamlessly between the cellular network and a broadband Internet connection in order to make phone calls; this is done with the help of femtocell access points. These differ from WiFi access points because they basically act as smaller versions of signal repeaters, but they function in a similar way by broadcasting wireless signal from a broadband connection. From there, Sprint users will be able to tell that they are in an Airwave coverage area by the audio tones before making or receiving a call, according to the FAQ, and other services, such as voicemail and 911, will otherwise behave as if they were on a traditional cell network.

T-Mobile offers a very similar service, called HotSpot@Home, which uses Unlicensed Mobile Access (UMA) to transition seamlessly between the cell network and WiFi routers whenever they are available. T-Mobile's service costs a tad more than Airwave—it is $20 on top of the customer's monthly bill, and it requires the user to have a special, UMA-enabled phone in able to make use of the service. Airwave users won't need special handsets in order to use the service.

There is a small catch to Airwave, in that it's not all quite as seamless as Sprint would like us to think. Calls made within range of an Airwave area are free and unlimited, and the user can transition seamlessly to the cell network if they wander outside of the femtocell's range; the clock then begins ticking on your monthly plan minutes. However, calls that are initiated on the cell network cannot transition to Airwave —customers who want to take advantage of Airwave must hang up and reinitiate the call. In contrast, T-Mobile's service is seamless both ways, but calls initiated on the WiFi remain unlimited even after they transition to the cell network. Similarly, calls initiated on the cell network continue to be counted against plan minutes even after they have transitioned to WiFi.

Right now, access to Airwave is very limited—it is only available in select areas of Denver and Indianapolis. Sprint says that the service would be extended throughout those two cities and into Nashville in 2007, however, with a broader commercial deployment in 2008. AT&T just put out a request for proposal to suppliers in July for its own femtocell service, so this looks to be a technology poised to move further into the mainstream.

Jacqui Cheng
Jacqui is an Editor at Large at Ars Technica, where she has spent the last eight years writing about Apple culture, gadgets, social networking, privacy, and more. Emailjacqui@arstechnica.com//Twitter@eJacqui